2. What is a framebuffer device?

A framebuffer device is an abstraction for the graphic
hardware. It represents the frame buffer of some video
hardware, and allows application software to access the
graphic hardware through a well-defined interface, so
that the software doesn't need to know anything about
the low-level interface stuff [Taken from Geert
Uytterhoeven's framebuffer.txt in the linux kernel
sources]